Refrigeration machine and method of operation



Jan. 30, 1968 w, CLARK ET AL 3,365,900

REFRIGERATION MACHINE AND METHOD O'F OPERATION Filed Aug. 1. 1966INVENTORS. E. CLARK.

WILLIAM JAMES W. ENDRESS.

ATTORNEY.

United States Patent 3,365,900 REFRIGERATION MACHINE AND METHOD OFOPERATION William E. Clark and James W. Endress, Syracuse, N.Y.,

assiguors to Carrier Corporation, Syracuse, N.Y., a corporation ofDelaware Filed Aug. 1, 1966, Ser. No. 569,376 Claims. (Cl. 62-415)ABSTRACT OF THE DISCLOSURE A refrigeration machine having a subcoolerfor lowering the temperature of the condensed refrigerant whereinrefrigerant flow to the evaporator is regulated by a valve between thesubcooler and the evaporator which is controlled in response to therefrigerant level upstream of the subcooler to maintain high liquidrefrigerant level therein while permitting forced feed of refrigeranttherethrough for maximum subcooler efiiciency.

This invention relates to a refrigeration machine. More particularly,this invention relates to a refrigeration machine having means thereinto subcool condensed refrigerant. Still more particularly, thisinvention relates to a refrigerant flow control particularly adapted toincrease the efficiency of the refrigerant subcooler.

In high tonnage refrigeration machines, a compressor is arranged toextract gaseous refrigerant from an evaporator and pump the compressedrefrigerant to a condenser where the refrigerant is cooled andcondensed. The liquid refrigerant in the condenser is ordinarily passedthrough a refrigerant metering device to the evaporator. The evaporatorcontains a multiplicity of tubes, usually referred to as a tube bundle,through which the medium to be cooled is passed in heat transferrelation with the refrigerant in the evaporator, cooling the medium andevaporating the refrigerant.

To increase the efficiency of the machine, it is desirable to cool thecondensed refrigerant to a temperature below condensing temperaturebefore it is passed to the evaporator. To accomplish this, a tube bundleis provided in a chamber at the bottom of the condenser or in a separateenclosure wherein condensed refrigerant may flow over the tube bundle inheat exchange relationship with a cooling medium flowing within thetubes.

For maximum subcooling, the refrigerant level in the subcooler must bemaintained to completely cover the tube bundle therein and therefrigerant flow rate across the tubes must be maximized. Presentsubcoolers utilize gravity flow of refrigerant therethrough.

The chief object of this invention is to provide an improvedrefrigeration machine. It is a further object of this invention toprovide a forced flow subcooler for a refrigeration machine. Anotherobject of this invention is to provide a novel refrigerant meteringdevice, particularly suited to accomplish the desired subcooler operation.

A further object is the provision of an improved method of operating arefrigeration machine wherein subcooler performance is greatly enhanced.

The objects of this invention are attained by providing a refrigerantlevel sensing device on the condenser side of the refrigerant subcooleroperably connected to a refrigerant metering device on the evaporatorside of the subcooler.

Other objects and features of this invention will be apparent upon aconsideration of the ensuing specification and drawing in which thefigure is a schematic view of a refrigeration machine showing the heattransfer portion thereof in perspective with parts broken away forclarity.

Referring more particularly to the drawing, there is shown a shell 1having a partition 3 therein dividing the shell into an evaporatorsection 5 and a condenser section 7.

Evaporator section 5 has a tube bundle 9 therein for passage of themedium being cooled by the refrigeration machine. Condenser section 7has a tube bundle 11 therein for passage therethrough of cooling waterfrom a suitable source, such as a cooling tower (not shown). Arefrigerant motor-compressor 13 is provided for compressing the lowpressure refrigerant gas from evaporator section 5 to provide highpressure refrigerant gas to the condenser section 7. A subcooler chamber15 is provided, defined on the top by a portion of partition 3, on oneside by shell 1, on the other side by an upstanding wall 14 and on thebottom by plate 16. An opening 21 in partition 3 provides a passagewaybetween condenser section 7 and subcooler chamber 15 near one endthereof. An opening 23 in bottom plate 16 is provided near the other endof subcooler chamber 15 to provide a passageway for flow of refrigerantfrom subcooler chamber 15 into refrigerant metering box 18 to behereinafter described. A tube bundle 19 is provided in subcooler chamber15 for circulating cooling water therethrough to subcool the condensedrefrigerant that drains into chamber 15 from condenser section 7 throughopening 21. This cooling water may be passed through the subcooler tubebundle and then through the condenser tube bundle or the subcooler andcondenser tube bundles may be suppiied with cooling water from separatecircuits. Due to the large number of tubes in the tube bundle 19 and thedistance between opening 21 and opening 23, there is a sizeable pressuredrop across the subcooler. A principal feature of this inventioninvolves employing this pressure drop to create a forced feed, asopposed to a gravity feed, of refrigerant through the subcoolerincreasing the efficiency thereof in a manner to be later described.Refrigerant metering box 18 is provided for regulating the flow ofrefrigerant from condenser section 7 through subcooler chamber 15 toevaporator section 5. Refrigerant metering box 18 is comprised of twochambers 18A and 183. The bottom chamber 18B is defined on the bottom bya plate 28 on one side by an extension of a portion 14' of upstandingwall 14 of the subcooler chamber, on the other side by an upstandingwall 29, on the back by upstanding wall 30 and on the top by the bottomside of a portion of plate 16 and an extension 16' thereof. An opening31 in the bottom plate 28 provides a communication between chamber 18Band refrigerant passageway 32 for flow of refrigerant from chamber 188to the evaporator. The top chamber 18A is defined on the top by a plate33, on the back by the aforementioned wall 30, on the bottom by the topof the aforementioned extension 16, on one side by the aforementionedwall 29, and on the other side by a portion of the shell 1. It should benoted that a portion of the shell 1 extending from the back Wall 30 tothe front wall (not shown) and from the juncture of the partition 3 withshell 1 to the juncture of shell 1 with the top plate 33 is cut out,thereby providing a large opening 34 between upper chamber 18A andcondenser section 7 for flow of refrigerant from the condenser intochamber 18A. Refrigerant expansion means comprising a suitable valvemember 35 in opening 31, connected to a valve actuating mechanism (floatball) 36 disposed in upper chamber 18A by rod 37, regulates the flow ofrefrigerant from the condenser, through the subcooler, to theevaporator.

Considering the operation of the refrigeration machine at start-up,refrigerant vapor condensed on tube bundle 11 will collect on the topside of partition 3. Chamber 18A being empty of refrigerant, float ball36 will hold valve 35 closed. Refrigerant on partition 3 will flowthrough opening 21 into subcooler chamber 15 and through opening 34 intochamber 18A. Eventually, refrigerant flowing through opening 21 willfill up chamber 18B, subcooler chamber 15 and chamber 18A up to thebottom of opening 34. Further condensation of refrigerant will causerefrigerant to puddle on partition 3 and raise the refrigerant level inchamber 18A high enough to cause float ball 36 to rise and partiallyopen valve 35.

From this point on, the float controlled valve will maintain the properflow of refrigerant to the evaporator to keep the subcooler tube bundlesubmerged at all times.

It should be noted that by placing the refrigerant Valve on theevaporator side of the subcooler and the level sensor (float orequivalent) on the condenser side as shown in the drawing, liquidrefrigerant is forced through the subcooler. This forced flow ofrefrigerant causes a greater scrubbing action by the refrigerant on thesubcooler tube bundle greatly increasing the heat transfer efficiencytherebetween as compared to subcoolers utilizing gravity flow ofrefrigerant therethrough.

While we have described a preferred embodiment of our invention, it isto be understood that our invention is not limited thereto, but may beotherwise embodied within the scope of the following claims.

We claim:

1. A refrigeration machine comprising a refrigerant compressor; acondenser; and an evaporator connected to form a closed circuit for theflow of refrigerant, means defining a subcooler chamber for reducing thetemperature of condensate formed in the condenser; refrigerant expansionmeans interposed between the subcooler chamber and the evaporator, saidexpansion means including a valve member regulating flow of refrigerantfrom the subcooler chamber to the evaporator, valve actuating mechanismoperably associated with the valve member, said subcooler chamber havingcommunication with the condenser and with the evaporator so thatcondensate formed in the condenser may flow through the subcoolerchamber to the evaporator, said valve actuating mechanism beingresponsive to the level of liquid refrigerant upstream of the subcoolerchamber whereby the flow of refrigerant to the evaporator is regulatedto continuously establish a predetermined quantity flow of refrigerantin the subcooler chamber.

2. A refrigeration machine as described in claim 1 wherein said valveactuating mechanism responds to the level of liquid refrigerant in thecondenser.

3. A refrigeration machine as described in claim 1 including arefrigerant metering box communicating with the subcooler chamber, saidbox containing said valve member.

4. A refrigeration machine according to claim 1 wherein said meansdefining a subcooler chamber includes a first passageway at one endthereof for receiving condensed refrigerant from said condenser and asecond passageway at the other end thereof for discharge of refrigerantfrom the subcooler chamber so as to assure passage of condensedrefrigerant the full length of the chamber for maximum subcoolingthereof.

5. The method of operating a refrigeration machine including acompressor, a condenser, a liquid refrigerant subcooler having meanstherein for passage of a cooling medium therethrough, a refrigerantexpansion device, and an evaporator connected to form a closed circuitfor the flow of refrigerant which consists in the steps of:

collecting liquid refrigerant in the high pressure side of the machine,

passing the liquid refrigerant through the subcooler in heat exchangerelationship with the cooling medium flowing therethrough, and

controlling passage of refrigerant from the subcooler through therefrigerant expansion device to the evaporator in response to apredetermined level of collected liquid refrigerant to create a pressuredrop across said subcooler to provide a forced flow of liq idrefrigerant therethrough.

References Cited UNITED STATES PATENTS 2,791,105 5/1957 Aronson 625092,921,446 1/1960 Zulinke 62-117 3,067,590 12/1962 Wood 62-335 3,315,4854/1967 Clark et al. 62-504 LLOYD L. KING, Primary Examiner.

